Inkjet printers are well-known. In these types of printers, droplets of ink are ejected from orifices in a printhead as the printhead scans across a medium. In certain types of inkjet printers, disposable print cartridges, each containing a printhead and a supply of ink, are installed in a scanning carriage. When the supply of ink is depleted, the print cartridge is disposed of. This results in a fairly expensive cost per sheet of printing.
Another type of inkjet printer allows the user to replace the ink supply in the scanning carriage without disposing of the printhead itself. In both of the cases described above, the scanning carriage supports the ink supply for the printhead. Since the capacity of the ink container must be fairly large to avoid changing ink supplies frequently, the carriage must be fairly large. This large carriage places a limit on reducing the size of the inkjet printer.
To overcome the disadvantages of the "on-axis" ink supplies, printers with off-axis ink supplies have been developed which use an ink supply not carried on the scanning carriage. A flexible tube connects the off-axis ink supply to the scanning printhead. One problem with these off-axis ink delivery systems is that the height difference between the printhead and the ink supply is directly related to the ink pressure to the printhead. Therefore, there is a high likelihood that ink will drool out of the printhead nozzles if the printer is tilted or tipped over. Further, the momentum of the ink in the flexible tube as the carriage scans causes fluctuations in the pressure of the ink applied to the printhead.
What is needed is an ink delivery system for an inkjet printer which does not suffer from the various drawbacks of the existing inkjet printers described above.